Function prepare_commodities_graph_for_validation

fn prepare_commodities_graph_for_validation(
    base_graph: &CommoditiesGraph,
    processes: &ProcessMap,
    commodities: &CommodityMap,
    time_slice_info: &TimeSliceInfo,
    region_id: &RegionID,
    year: u32,
    time_slice_selection: &TimeSliceSelection,
) -> CommoditiesGraph

Prepares a graph for validation with validate_commodities_graph.

It takes a base graph produced by create_commodities_graph_for_region_year, and modifies it to account for process availabilities and commodity demands within the given time slice selection, returning a new graph.

Commodity demands are represented by the Demand node. We only add edges to the Demand node for commodities with the same time_slice_level as the selection. Other demands can be ignored since this graph will only be validated for commodities with the same time_slice_level as the selection.